The self-aligning roller bearings and barrel roller bearings denoted by the term self-aligning antifriction bearings are used in applications in which an angular error between the housing and the shaft has to be compensated. Through the use of the rolling element roller with line contact between the outer and inner ring, these bearings are suitable for high loads. If the load upon the antifriction bearing is low, the rollers tend to slide between the raceways due to the absence of rolling contact. The rotation speed of the cage carrying the rolling elements falls to normal under rolling contact. In the event of an abrupt rise in load upon the rolling element, the antifriction bearing, the rolling element, which then enters into engagement between the outer and inner ring, must accelerate the whole of the cage carrying all the other rolling elements, within fractions of a second, to the correct rotation speed. This acceleration process generates high forces in the cage. The resultant slippage between the accelerated rollers and the raceways of the outer and inner ring leads to damage to the rolling elements and to the raceways.
The aforesaid problem arises, for example, in applications in which the rolling elements, in normal operation, are only put under low load. In the event of abrupt increases in load, the self-aligning antifriction bearings are briefly subjected to peak loads which can lead to the effect described above.
In DE 8803970 U1, a radial antifriction bearing is described, in which rollers and balls are jointly used as rolling elements. The self-aligning antifriction bearing of the generic type is provided with at least a first row of rolling elements and a second row of rolling elements adjacent to the first row of rolling elements. Each of the rows has a row of barrel rollers disposed peripherally about a bearing center axis of the self-aligning antifriction bearing. In addition, in the self-aligning antifriction bearing, a row of balls is disposed. In the bearing according to DE 8803970 U1, the basic load rating is said to be increased by the additional row of balls. The consequences of brief increases in load are not solved with this realization.
In such types of bearings of the prior art, the balls, because of their punctual contact surface with the raceways during operation of the self-aligning antifriction bearing, are intent upon assuming a kinematically optimal position. This generally leads to constrained axial motions on the part of the balls. The balls are consequently supported, especially laterally, in the cage pockets against the forces arising from the constrained motions. Increased friction, combined with higher operating temperatures and wear in the ball pockets, are the result. The mountings for the balls in the pockets are endangered and may possibly suffer premature wear. A cage described in DE 8803970 U1, due to the ball pockets situated axially between the pockets for the rollers, can only be produced at relatively high cost.